1. Field of the Invention
The present invention relates to an absorbent article, such as disposable diaper, sanitary napkin or the like, with a surface structural body of continuous filaments.
2. Description of the Related Art
The conventional absorbent article, such as disposable diaper, sanitary napkin or the like, has a liquid impermeable backing sheet on back side of an absorbent core, and a liquid permeable surface sheet on surface side as liquid receiving side.
The surface sheet of the conventional absorbent article is formed of a liquid permeable non-woven fabric, a synthetic resin film formed with a large number of pores or through holes. However, since the conventional surface sheet has a uniform thickness in a width direction, it is difficult to appropriately fit on the discharge region of a wearer. This results in that a gap is formed between the discharge region and the surface sheet to possibly cause lateral leakage of discharged liquid along the surface sheet.
Therefore, for example, in Japanese Unexamined Patent Publication No. Heisei 9-322908, there has been disclosed an absorbent article in which a liquid permeable surface layer is deformed and bulged toward a wearer at the center portion thereof to form a projecting ridge (bank) for fitting on the discharge region of a wearer.
On the other hand, for preventing lateral leakage of liquid along the foregoing surface layer, there is an absorbent article in which leakage preventing walls extending in longitudinal direction are formed on laterally opposite side portions of the surface sheet. The leakage preventing wall is formed with a hydrophobic sheet raising from the surface sheet and an elastic member provided at the top portion of the hydrophobic sheet. The hydrophobic sheet is raised from the surface sheet by elastic contraction force of the elastic member.
However, in the absorbent article disclosed in Japanese Unexamined Patent Publication No. Heisei 9-322908, since the surface layer is deformed and bulged at the center portion thereof for providing a projecting portion at the center portion of the absorbent article, the structure of the surface layer becomes quite complicate to cause high manufacturing cost.
On the other hand, in case of the absorbent article having the leakage preventing walls, there is required manufacturing process to join the hydrophobic sheet with the surface sheet and to join the elastic member to the hydrophobic sheet. Such additional process steps inherently limit lowering of manufacturing cost.
The present invention has been worked out in view of the shortcoming in the prior art as set forth above. It is therefore an object of the present invention to provide an absorbent article, in which a bulged portion to be fitted to discharge region of a wearer or laterally opposite banks for preventing leakage of liquid can be manufactured through quite simple process, and which can provide soft contact feeling to the wearer""s skin.
According to the present invention, there is provided an absorbent article comprising:
a liquid permeable surface structural body;
a backing sheet;
an absorbent core disposed between the surface structural body and the backing sheet,
the surface structural body being formed by stacking bundles of continuous filaments into at least two layers and partially fixing the continuous filaments of the respective layers together, the individual continuous filaments extending over the entire length of the respective layers,
wherein the layers include: a lower layer positioned adjacent to the absorbent layer; and an upper layer positioned away from the absorbent layer and having a smaller width than that of the lower layer, and the upper layer is located exclusively at a center portion or laterally opposite side portions of the lower layer.
Preferably, the lower layer has higher hydrophilicity than the upper layer. In this case, the upper layer may be formed of hydrophobic continuous filaments not subjected to hydrophilic treatment, and the lower layer may be formed of hydrophobic continuous filaments treated to be hydrophilic or of hydrophilic continuous filaments.
Also preferably, filament density of the upper layer is different from filament density of the lower layer. In this case, more preferably, filament density of the lower layer is higher than filament density of the upper layer.
The surface structural body may further comprise an intermediate layer of the continuous filaments between the lower layer and the upper layer, and widths of the lower layer, the intermediate layer and the upper layer may be varied in descending order from the lower layer to the upper layer. In this case, hydrophilicities of the upper layer, the intermediate layer and the lower layer may be varied in ascending order from the upper layer to the lower layer. For example, the upper layer may be formed of hydrophobic continuous filaments not subjected to hydrophilic treatment. Alternatively, the lower layer, the intermediate layer and the upper layer may have mutually different filament densities. In this case, preferably, filament densities of the lower layer, the intermediate layer and the upper layer are varied in ascending order from the upper layer to the lower layer.
The upper layer may be located exclusively at laterally opposite side portions of the lower layer, and the upper layer may be water repellent.
In the present invention, since the surface structural body is formed of the continuous filaments to have low density and high bulkiness, it provides soft contact feeling to the skin of a wearer. Especially since the continuous filaments extend over the entire length of the respective layers of the surface structural body, no fiber end appears on the surface thereof. Therefore, the surface of surface structural body is so smooth.
In the surface structural body formed of the continuous filaments, by providing a difference in hydrophilicity and/or filament density between the upper and lower layers, liquid permeability and effect of preventing the liquid from flowing back can be enhanced.
The surface structural body having a difference in hydrophilicity and/or filament density between layers can be manufactured quite simply by continuously feeding continuous filaments of different hydrophilicities and/or filament densities and partially fixing the continuous filaments.